Corporations are one of the oldest and most widespread business entities. By selling stock publicly, they allow massive accumulations of capital in ways that are difficult for other business entities. Since their development, much law developed surrounding their various stakeholders, particularly for how stock can and cannot be sold.
Understanding how corporations work is essential for understanding the legal environment of business, even if you do not create or are employed by one. Understanding rules for buying and selling stock is equally crucial, especially to avoid charges of insider trading.